Air infiltration induced by heating appliances.

Infiltration heat losses due to heating appliances located within the living space are normally evaluated by reducing the conversion efficiency of the boiler, with no consideration for the fluid dynamic interaction between boiler, chimney and building. Purpose of this work is to develop a simplified mathematical model of the overall (building + boiler + chimney) system, suitable to calculate the pressure distribution and air flow rate in the building induced by the simultaneous effect of natural forces and the exhaust system. Inside pressure and air flows across the envelope, through the boiler, the draft diverter, and the stack are calculated by means of a steady-state model. Results are presented as a parametric analysis which points out the dependence of air infiltration rates on factors such as envelope permeability and weather conditions, and the dependence of stack flow rate on weather parameters.